Charge-discharge control device, charge-discharge control system, and computer program product

ABSTRACT

According to an embodiment, a charge-discharge control device includes a receiving unit and a group controller. The receiving unit is configured to receive schedule information that indicates a schedule time at which a plurality of electric power devices, each having at least either a charging function or a discharging function, performs at least either charging or discharging. The group controller is configured to, according to the schedule information, perform grouping in such a way that each of the electric power devices belongs to either one of a charging group for performing charging and a discharging group for performing discharging, and control, on a group-by-group basis, each of the electric power devices put in the charging group and each of the electric power devices put in the discharging group.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2012-076624, filed on Mar. 29, 2012; theentire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a charge-dischargecontrol device, a charge-discharge control system, and a computerprogram product.

BACKGROUND

It is known that the result of measuring electricity consumption ofelectricity users or the result of measuring the electricity generatedby photovoltaic power generation is sent to a server for the purpose ofelectric energy management. Moreover, it is a known fact thatlarge-scale energy management, on a larger scale than households orbuildings, is performed via a network.

However, if there is an increase in the number of electric power devicesthat perform discharging or charging and that are connected to anetwork, it leads to an overload in the amount of information that iscommunicated via the network. As a result, it becomes difficult toperform communication in an efficient manner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system configuration diagram illustrating an exemplaryconfiguration of a charge-discharge control system according to anembodiment;

FIGS. 2A and 2B are configuration diagrams each illustrating aconfiguration of a ENERGY STORAGE SYSTEM connected to a charge-dischargecontrol device;

FIG. 3 is a configuration diagram illustrating a connection between thecharge-discharge control device and a ENERGY STORAGE SYSTEM;

FIG. 4 is a configuration diagram illustrating a connection between twocharge-discharge control devices and a consumer-side electric powersystem;

FIG. 5 is a conceptual diagram illustrating a condition in which acollection of a plurality of ENERGY STORAGE SYSTEMs is controlled as asingle logical BATTERY UNIT;

FIG. 6 is a functional block diagram illustrating the functions of thecharge-discharge control device;

FIGS. 7A to 7D are diagrams illustrating a configuration ofcharacteristics information, a configuration of charge-discharge controlinformation, a configuration of feasibility information, and aconfiguration of dedicated device information, respectively;

FIG. 8 is a graph illustrating a relationship between the charging rate,the chargeable time, and the dischargeable time;

FIG. 9 is a diagram for explaining the state of management performed byan electric power control unit with respect to the total amount ofcharging and discharging;

FIG. 10 is a graph illustrating the state of management performed by theelectric power control unit with respect to the total amount of chargingand discharging;

FIG. 11 is a functional block diagram illustrating the functions of aPCS (FIRST CONTROL UNIT) in the ENERGY STORAGE SYSTEM;

FIGS. 12A to 12C are diagrams illustrating a configuration of accesscontrol information, a configuration of characteristics information, anda configuration of operation control information;

FIGS. 13A and 13B are diagrams illustrating a configuration ofcharge-discharge determination information and a configuration ofcharge-discharge electric power information;

FIG. 14 is a graph illustrating a case when discharge controlinstructions are received from two charge-discharge control devices;

FIG. 15 is a flowchart for explaining a sequence of operations performedby the charge-discharge control device;

FIG. 16 is a sequence diagram illustrating operation examples of thecharge-discharge control system;

FIGS. 17A to 17C are configuration diagrams illustrating configurationexamples of communication messages;

FIG. 18 is a graph illustrating an assigned discharge electric powerwith respect to the charge-discharge control device;

FIG. 19 is a schematic diagram that schematically illustrates theassignment of electric power in first-time grouping;

FIG. 20 is a graph illustrating a relationship between the rated chargeelectric power and the charge period; and

FIG. 21 is a schematic diagram that schematically illustrates theassignment of electric power in second-time grouping.

DETAILED DESCRIPTION

According to an embodiment, a charge-discharge control device includes areceiving unit and a group controller. The receiving unit is configuredto receive schedule information that indicates a schedule time at whicha plurality of electric power devices, each having at least either acharging function or a discharging function, performs at least eithercharging or discharging. The group controller is configured to,according to the schedule information, perform grouping in such a waythat each of the electric power devices belongs to either one of acharging group for performing charging and a discharging group forperforming discharging, and control, on a group-by-group basis, each ofthe electric power devices put in the charging group and each of theelectric power devices put in the discharging group.

An exemplary embodiment of a charge-discharge control system isdescribed below in detail with reference to the accompanying drawings.FIG. 1 is a system configuration diagram illustrating an exemplaryconfiguration of a charge-discharge control system 1 according to theembodiment. As illustrated in FIG. 1, the charge-discharge controlsystem 1 is, for example, a system for controlling the energy over awide area. The charge-discharge control system 1 includes an electricpower system side 10 and includes an CONSUMER SIDE 12 such as ahousehold, a building, or a factory.

The electric power system side 10 includes, for example, an electricpower plant (a power feeding control center) 20, a RENEWABLES 22, and aENERGY STORAGE SYSTEM 24. The CONSUMER SIDE 12 includes, for example, aconsumer-side electric power system 3, a charge-discharge control device(a consumer-side energy management system (EMS)) 5, and a smart meter 6.Moreover, for example, a charge-discharge control device 7 is installedas an energy management system (EMS) between the electric power systemside 10 and the CONSUMER SIDE 12. The charge-discharge control device 7controls, for example, the charging and the discharging of the entirecharge-discharge control system 1. The charge-discharge control device 5controls, for example, the charging and the discharging on the CONSUMERSIDE 12. Meanwhile, practically, the charge-discharge control device 5and the charge-discharge control device 7 may have the same functionsand the same configuration.

The electric power plant 20 generates a large amount of electric powerby making use of the hydraulic power, the thermal power, or the nuclearpower. The electric power plant 20 is connected to the charge-dischargecontrol device 7 via an electric power grid 14 and via a communicationnetwork (network) 16, and supplies (discharges) the electric power tothe electric power grid 14. The RENEWABLES 22 is, for example, aphotovoltaic power plant or a wind power plant, and generates electricpower by making use of the energy available in the natural world. TheRENEWABLES 22 is connected to the charge-discharge control device 7 viathe electric power grid 14 and via the communication network 16, andsupplies (discharges) the electric power to the electric power grid 14.

The ENERGY STORAGE SYSTEM 24 includes storage batteries (notillustrated) for performing charging and discharging, and is connectedto the charge-discharge control device 7 via the electric power grid 14and via the communication network 16. Moreover, the ENERGY STORAGESYSTEM 24 is connected to the RENEWABLES 22 via the electric power grid14, and is used to store the surplus electric power generated by theRENEWABLES 22. In addition, with the aim of maintaining the electricquality such as the frequency or the voltage of the electric powersystem side 10, the ENERGY STORAGE SYSTEM 24 is also used to implement afunction called ancillary service (short-period control) in which powerconditioning is done on the second time scale in response to momentaryload changes so as to stabilize the electric power system side 10.Meanwhile, the ENERGY STORAGE SYSTEM 24 can be replaced with, forexample, a heat accumulator device that discharges heat. In theembodiment, the entire transmission and distribution network that isused in supplying the electric power from the electric power system side10 to the CONSUMER SIDE 12 is referred to as the electric power grid 14.

The consumer-side electric power system 3 includes, for example, aphotovoltaic power generating device 30, an electric vehicle (EV) system32, and a ENERGY STORAGE SYSTEM 4. The consumer-side electric powersystem 3 is connected to the charge-discharge control device 7 via theelectric power grid 14 and via the communication network 16; and thesmart meter 6 is installed between the consumer-side electric powersystem 3 and the charge-discharge control device 7. The charge-dischargecontrol device 5 is connected to the charge-discharge control device 7,the consumer-side electric power system 3, and the smart meter 6 via thenetwork 16; and functions as a charge-discharge control device thatcontrols the consumer-side electric power system 3 and the smart meter6. Herein, for example, the smart meter 6 has the function of ameasurement apparatus for measuring the electric energy that has beenconsumed by the consumer-side electric power system 3 and sending themeasurement result to an administration server (not illustrated) and tothe charge-discharge control device 7.

The photovoltaic power generating device 30 generates electricity bymaking use of the sunlight and stores the generated electricity in, forexample, the ENERGY STORAGE SYSTEM 4. The EV system 32 is connected tothe electric power grid 14 and the network 16 via a charging device (notillustrated). The ENERGY STORAGE SYSTEM 4 includes storage batteries(not illustrated) for performing charging and discharging, and is usedto implement a function called peak shift (day-long operation) in whichthe electricity is stored during the nighttime and used during thedaytime.

The charge-discharge control device 7 considers the CONSUMER SIDE 12,which includes the ENERGY STORAGE SYSTEM 4 and the EV system 32, as asingle logical CONSUMER SIDE BATTERY UNIT 8; and considers the electricpower system side 10, which includes the ENERGY STORAGE SYSTEM 24, as asingle logical system-side BATTERY UNIT 9. Alternatively, thecharge-discharge control device 7 may consider the charge-dischargecontrol device 5, the smart meter 6, and the photovoltaic powergenerating device 30 as the CONSUMER SIDE BATTERY UNIT 8; and canconsider the electric power plant 20 and the RENEWABLES 22 as thesystem-side BATTERY UNIT 9. Still alternatively, the charge-dischargecontrol device 7 either may consider all storage batteries included inthe charge-discharge control system 1 or can consider an arbitrarynumber of storage batteries as a single logical BATTERY UNIT. Forexample, the charge-discharge control device 7 can consider all of aplurality of CONSUMER SIDE storage batteries 8 and all of a plurality ofsystem-side storage batteries 9 as a logical BATTERY UNIT.

FIG. 2A is a configuration diagram of the ENERGY STORAGE SYSTEM 4connected to the charge-discharge control device 7, and FIG. 2B is aconfiguration diagram of a ENERGY STORAGE SYSTEM 4 a connected to thecharge-discharge control device 7. As illustrated in FIG. 2A, the ENERGYSTORAGE SYSTEM 4 is an electric power device including a BATTERY UNIT 40and a PCS (FIRST CONTROL UNIT) 42. The BATTERY UNIT 40 is, for example,a battery management unit (BMU) that includes a plurality of batterycells (not illustrated) and an internal processor (not illustrated), andthat performs charging and discharging of electric power under thecontrol of the PCS (FIRST CONTROL UNIT) 42. Herein, the PCS (FIRSTCONTROL UNIT) 42 functions as, for example, a power conditioning system(PCS). The PCS (FIRST CONTROL UNIT) 42 is connected to thecharge-discharge control device 7 via the electric power grid 14 and viathe network 16, and is connected to the BATTERY UNIT 40 via the electricpower grid 14 and via a controller area network (CAN) 18.

More particularly, the BATTERY UNIT 40 notifies the PCS (FIRST CONTROLUNIT) 42 of the battery rated voltage, the maximum current value duringcharging, the charging rate SOC (State Of Charge), and the life rate SOH(State Of Health). Then, the PCS (FIRST CONTROL UNIT) 42 performs, forexample, direct current-alternating current conversion and voltagefluctuation control.

As illustrated in FIG. 2B, the EV system 32 includes a BATTERY UNIT 320and a second control unit 322. The EV system 32 is connected to abattery charger 42 a, and in turn gets connected to the electric powergrid 14 and the network 16 via the battery charger 42 a.

The BATTERY UNIT 320 is, for example, a battery management unit (BMU)that includes a plurality of battery cells (not illustrated) and aninternal processor (not illustrated), and that performs charging anddischarging of the electric power. The second control unit 322 isconnected to the BATTERY UNIT 320 via the electric power grid 14 and theCAN 18, and is connected to the battery charger 42 a via the electricpower grid 14 and the CAN 18. Then, the second control unit 322 relaysthe communication between the battery charger 42 a and the BATTERY UNIT320.

The battery charger 42 a functions as a power conditioning system (PCS)mentioned above. Thus, by getting connected to the battery charger 42 a,the EV system 32 constitutes the ENERGY STORAGE SYSTEM 4 a that isequivalent to the ENERGY STORAGE SYSTEM 4.

FIG. 3 is a configuration diagram illustrating a connection examplebetween the charge-discharge control device 7 and the ENERGY STORAGESYSTEM 24 on the electric power system side 10. As illustrated in FIG.3, on the electric power system side 10, the charge-discharge controlsystem 1 includes two ENERGY STORAGE SYSTEMs 24 that are connected totwo charge-discharge control devices 7. The configuration can be suchthat each ENERGY STORAGE SYSTEM 24 is controlled by eachcharge-discharge control device 7. In this way, in the charge-dischargecontrol system 1, a plurality of ENERGY STORAGE SYSTEMs 24 can beconnected to each other so that a large storage capacity is secured thatmatches the large storage capacity of an electric power plant. Then, thefunction called ancillary service can be implemented to deal withmomentary load changes. Meanwhile, in the case when the electric powerstored across a plurality of areas is interchanged, it is desirable thata plurality of charge-discharge control devices 7 are installed in thecharge-discharge control system 1. In the embodiment, thecharge-discharge control device 7 performs grouping to divide thesystem-side BATTERY UNIT 9 into a plurality of groups.

FIG. 4 is a configuration diagram illustrating a connection examplebetween the charge-discharge control device 7, the charge-dischargecontrol device 5, and the consumer-side electric power system 3 on theCONSUMER SIDE 12. As illustrated in FIG. 4, when the charge-dischargecontrol device 7 and the charge-discharge control device 5 control theconsumer-side electric power system 3, the charge-discharge controldevice 7 or the charge-discharge control device 5 performs grouping todivide the CONSUMER SIDE BATTERY UNIT 8 into a plurality of groups. Forexample, the charge-discharge control device 7 performs grouping todivide the CONSUMER SIDE BATTERY UNIT 8 as well as the system-sideBATTERY UNIT 9 into a charging group for performing charging and into adischarging group for performing discharging.

FIG. 5 is a conceptual diagram illustrating a condition in which thecharge-discharge control device 7 controls a collection of a pluralityof ENERGY STORAGE SYSTEMs 4 as a single logical BATTERY UNIT. Asillustrated in FIG. 5, the charge-discharge control device 7 groups thecollection of the plurality of ENERGY STORAGE SYSTEMs 4 into, forexample, a ENERGY STORAGE GROUP A, a ENERGY STORAGE GROUP B, and aENERGY STORAGE GROUP C; performs control on a group-by-group basis; and,for example, assigns shared use rights to a plurality of users. Thus,the charge-discharge control device 7 may group a plurality of ENERGYSTORAGE SYSTEMs 4 performing charging into a plurality of differentcharging groups. Similarly, the charge-discharge control device 7 maygroup a plurality of ENERGY STORAGE SYSTEMs 4 performing discharginginto a plurality of different discharging groups.

Explained below in detail are the functions of the charge-dischargecontrol device 7. FIG. 6 is a functional block diagram illustrating thefunctions of the charge-discharge control device 7. The charge-dischargecontrol device 7 functions as a computer and includes a supply-demandadjusting unit 70, a communicating unit 71, an information control unit72, a memory unit 73, a group control unit 74, and an electric powercontrol unit 75.

The supply-demand adjusting unit 70 monitors the electricity and thefrequency condition on the electric power system side 10 of an electricpower provider and on the CONSUMER SIDE 12. Moreover, in order toprevent electricity failure due to electric power shortage, thesupply-demand adjusting unit 70 performs discharging control andcharging control with respect to the ENERGY STORAGE SYSTEM 24 and theENERGY STORAGE SYSTEM 4.

The communicating unit 71 includes a transmitting unit 710 and areceiving unit 712, and performs communication via the network 16.

The information control unit 72 includes a determining unit 720, andprocesses and controls the information that is obtained via thecommunicating unit 71. For example, the information control unit 72obtains a communication message, which is related to electric energyinformation or access control of the BATTERY UNIT 40 that is requiredfor performing charging and discharging control, from the ENERGY STORAGESYSTEM 4 via the communicating unit 71; and accordingly performsprocessing and control.

The determining unit 720 determines, according to feasibilityinformation (described later), whether or not it is allowed tosimultaneously put an electric power device such as the ENERGY STORAGESYSTEM 4 in a plurality of different charging groups. Similarly, thedetermining unit 720 also determines, according to the feasibilityinformation (described later), whether or not it is allowed tosimultaneously put an electric power device such as the ENERGY STORAGESYSTEM 4 in a plurality of different discharging groups.

The memory unit 73 is used to store characteristics information,charge-discharge control information, the feasibility information, anddedicated device information. FIGS. 7A to 7D are diagrams illustratingconfiguration examples of the characteristics information, thecharge-discharge control information, the feasibility information, andthe dedicated device information.

The characteristics information points to the information that ispeculiar to the BATTERY UNIT 40 and that is required for performingcharging and discharging control. As illustrated in FIG. 7A, thecharacteristics information contains rated charge-discharge electricpower indicated in unit watt (W: watt) with respect to the BATTERY UNIT;rated capacity indicated in unit watt hour (Wh: watt hour); chargingrate (SOC: State Of Charge) indicted in unit percentage; dischargeabletime corresponding to SOC; chargeable time corresponding to SOC; andtype corresponding to SOC.

In the constant current charging method that is the commonly-usedcharging method for charging a BATTERY UNIT, the electric energy (amountof current) that is input-output by the battery cells in the BATTERYUNIT 40 remains constant until the SOC indicated in percentage reaches apredetermined threshold value. For example, as illustrated in FIG. 8,with respect to the ENERGY STORAGE SYSTEM 4, the value of SOC isobtained from the BATTERY UNIT 40 so that it becomes possible tocalculate the dischargeable time and the chargeable time (horizontalaxis of graph), the rated charge-discharge electric power (vertical axisof graph), and the electric energy (product of chargeable-dischargeabletime and electric power) that is required for charging and discharging.Thus, the characteristics information may contain condition calculatinginformation that enables derivation of the chargeable time and the ratedvalue.

In constant current charging, the BATTERY UNIT 40 has thecharacteristics that, when the SOC exceeds the predetermined thresholdvalue, the amount of current required for charging is minimized.Meanwhile, the electric energy at the time of controlling charging ordischarging can be indicated not only as the electric energy in unitwatt time (Wh: watt hour) but also as the amount of current in unitampere time (Ah: ampere hour) or as the voltage (Vh: volt hour) in unitvolt time.

The charge-discharge control information is used in identifying thecharge-discharge operation condition of the ENERGY STORAGE SYSTEM 4. Asillustrated in FIG. 7B, the charge-discharge control informationcontains a target BATTERY UNIT, charge-discharge information, andcharge-discharge details. The target BATTERY UNIT indicates the BATTERYUNIT 40 that is to be controlled for charge-discharge. Thecharge-discharge information contains an “already set” status or a “notset” status that are used in identifying whether or not scheduleinformation is set that indicates the scheduled time when the ENERGYSTORAGE SYSTEM 4 is controlled by means of scheduled operations. Thecharge-discharge details indicate whether charging is to be performed ordischarging is to be performed.

For example, in order to prevent temporary interruption from occurringin the power supply of the electric power grid 14, it is desirable thatthe ENERGY STORAGE SYSTEM 4 is controlled by means of on-demandoperations. On the other hand, in the case of performing control atrelatively lenient time intervals such as during the nighttime, it isdesirable that the ENERGY STORAGE SYSTEM 4 is controlled by means ofscheduled operations in which the schedule of operation timings is setfor performing charging and discharging control.

The feasibility information is used in identifying an electric powerdevice such as the ENERGY STORAGE SYSTEM 4 that can (or is allowed to)simultaneously receive a plurality of different charging controls (ordischarging controls). As illustrated in FIG. 7C, the feasibilityinformation contains information that indicates such a ENERGY STORAGESYSTEM 4 which is allowed to simultaneously receive a plurality ofcharging controls or discharging controls (which is allowed to performsharing). For example, the feasibility information indicates whether ornot it is allowed for an electric power device such as the ENERGYSTORAGE SYSTEM 4 to simultaneously belong to a plurality of differentcharging groups. The feasibility information may also indicate whetheror not it is allowed for an electric power device such as the ENERGYSTORAGE SYSTEM 4 to simultaneously belong to a plurality of differentdischarging groups.

In FIG. 7C, it is illustrated that the ENERGY STORAGE SYSTEM 4 (ENERGYSTORAGE SYSTEM A) can be subjected to charge-discharge control by aparticular charge-discharge control device 7 in a particular period andcan be subjected to charge-discharge control by a differentcharge-discharge control device 7 in another period. Meanwhile, when thecharge-discharge control device 7 performs control of a plurality ofENERGY STORAGE SYSTEMs 4, there exists a plurality of sets ofinformation of the storage batteries that are allowed to be controlled.

The dedicated device information is the information indicating whetheran electric power device performs charging or performs discharging. Asillustrated in FIG. 7D, the dedicated device information indicates thatthe photovoltaic power generating device 30 (a photovoltaic powergenerating device A) and a wind power generating device A are electricpower devices that perform only discharging. Similarly, the dedicateddevice information indicates that a heat accumulator device A (such asthe ENERGY STORAGE SYSTEM 24) is an electric power device that performsonly charging.

According to the schedule information, the electric power control unit75 performs grouping in such a way that each electric power deviceeither belongs to a charging group for performing charging or adischarging group for performing discharging, and controls, on agroup-by-group basis, each of the electric power devices, such as theENERGY STORAGE SYSTEM 4, in each charging group as well as in eachdischarging group. Moreover, according to the determination result ofthe determining unit 720 and according to the schedule information, thegroup control unit 74 performs grouping in such a way that the electricpower device that is not allowed to simultaneously belong to a pluralityof charging groups is not simultaneously put in a plurality of charginggroups and in such a way that electric power devices, such as theBATTERY UNIT 40, that perform charging belong to one or more charginggroups; and controls the electric power devices put in each charginggroup on a group-by-group basis. Similarly, according to thedetermination result of the determining unit 720 and according to theschedule information, the group control unit 74 performs grouping insuch a way that the electric power device, such as the ENERGY STORAGESYSTEM 4, that is not allowed to simultaneously belongs to a pluralityof discharging groups is not simultaneously put in a plurality ofdischarging groups and in such a way that electric power devices thatperform discharging belong to one or more discharging groups; andcontrols the electric power devices in each discharging group on agroup-by-group basis.

Moreover, as the validity time limit of charging groups or discharginggroups, the group control unit 74 sets the interval of time in which theschedule time for performing charging or discharging as specified in theschedule information ends for the first time within a charging group orwithin a discharging group. Furthermore, the group control unit 74 againperforms grouping with respect to the charging groups or the discharginggroups to which belonged an electric power device that is disconnectedfor communication from the communicating unit 71, or again performsgrouping with respect the charging groups or the discharging groups towhich belonged an electric power device that has reached the validitytime limit.

The electric power control unit 75 includes a calculating unit 750 thatcalculates the total amount of charging of the charging groups as wellas calculates the total amount of discharging of the discharging groupsby referring to electric power characteristics such as rated valuesincluded in the characteristic information. Moreover, according to theassigned amount of electric power for charging or the assigned amount ofelectric power for discharging that is set for an electric power deviceand according to the condition calculating information mentioned above,the calculating unit 750 calculate the total amount of charging of eachcharging group or the total amount of discharging of each discharginggroup.

Furthermore, with respect to a virtual BATTERY UNIT that has beenobtained by grouping by the group control unit 74 (i.e., with respect toa single logical BATTERY UNIT that is a collection of a plurality ofENERGY STORAGE SYSTEMs 4), the electric power control unit 75 managesthe total amount of charging and discharging as well as issuescharge-discharge control instructions. FIG. 9 is a diagram forexplaining the state of management performed by the electric powercontrol unit 75 with respect to the total amount of charging anddischarging. FIG. 10 is a graph illustrating the state of managementperformed by the electric power control unit 75 with respect to thetotal amount of charging and discharging.

As illustrated in FIG. 9, assume that a group A that is a virtual ENERGYSTORAGE GROUP includes a BATTERY UNIT A (the ENERGY STORAGE SYSTEM 4)and a BATTERY UNIT B (the ENERGY STORAGE SYSTEM 4). During a timeinterval t1; if, for example, the BATTERY UNIT A discharges the electricpower of 100 W and the BATTERY UNIT B discharges the electric power of200 W, then the total amount of discharging becomes equal to 300 W.During a time interval t2, the BATTERY UNIT B performs charging ofelectric power. Meanwhile, alternatively, the BATTERY UNIT B (the ENERGYSTORAGE SYSTEM 4) can exist as another virtual ENERGY STORAGE GROUPnamed group B and can perform charging of electric power within a timeinterval t3.

The storage batteries are not allowed to perform discharging andcharging at the same time because of the reason that the operationsbecome unclear. For example, with respect to a particular group, thecharge-discharge control device 7 cannot perform control to let theBATTERY UNIT A discharge the electric power of 100 W and let the BATTERYUNIT B charge the electric power of 100 W at the same time. For thatreason, the charge-discharge control device 7 performs grouping in sucha way that each electric power device belongs to either a charging groupfor performing charging or a discharging group for performingdischarging, and controls the electric power devices in each charginggroup and the electric power devices in each discharging group.Moreover, the charge-discharge control device 7 may perform control withrespect to a plurality of different charging groups that performcharging and with respect to a plurality of different discharging groupsthat perform discharging.

With respect to the ENERGY STORAGE SYSTEM 4 that operates on theon-demand basis, the charge-discharge control device 7 specifies theamount of charging or the amount of discharging; while with respect tothe ENERGY STORAGE SYSTEM 4 that operates according to a schedule, thecharge-discharge control device 7 specifies the amount of charging orthe amount of discharging as well as specifies a time interval. Whensending a control instruction in the form of a communication message,the charge-discharge control device 7 can change the data model or thecommunication protocol according to the location. For example, thecharge-discharge control device 7 can make use of IEC61850-7-420 that isa standard for electricity infrastructure related to the control of adispersed power system such as the RENEWABLES 22; or can make use ofBACnet that is a standard for buildings; or can make use of ECHONET thatis used for Japanese households; or can make use of ZigBee (registeredtrademark) SEP 2 (SEP stands for Smart Energy Profile) that is used forEuropean households.

Explained below in detail are the functions of the ENERGY STORAGE SYSTEM4. FIG. 11 is a functional block diagram illustrating the functions ofthe PCS (FIRST CONTROL UNIT) 42 in the ENERGY STORAGE SYSTEM 4.Meanwhile, practically, the battery charger 42 a to which the EV system32 is connected may have the same functions and the same configurationas the PCS (FIRST CONTROL UNIT) 42.

The PCS (FIRST CONTROL UNIT) 42 includes an electric power supplyingunit 420, a first communicating unit 421, a second communicating unit422, an information obtaining unit 423, an information control unit 424,an access control unit 425, a memory unit 426, and a charge-dischargemanaging unit 427. The electric power supplying unit 420 performs directcurrent-alternating current conversion, performs power frequencymonitoring, and performs voltage fluctuation detection and control.Moreover, under the control of the charge-discharge control device 7,the electric power supplying unit 420 performs charge-discharge controlwith respect to the BATTERY UNIT 40.

The memory unit 426 is used store access control information,characteristics information, and operation control information. FIGS.12A to 12C are diagrams illustrating configuration examples of theaccess control information, the characteristics information, and theoperation control information stored in the memory unit 426.

The access control information is related to the feasibility informationdescribed above and is used in identifying whether or not it is possibleto simultaneously receive charge-discharge control instructions from aplurality of charge-discharge control devices 7. As illustrated in FIG.12A, the access control information contains information about a controlauthorization residual quantity and about devices having controlauthorization. For example, when simultaneous control from twocharge-discharge control devices 7 is allowed, the ENERGY STORAGE SYSTEM4 is simultaneously sharable and the control authorization residualquantity has the initial value of “2”. Thus, when the controlauthorization residual quantity is “2”, it means that the ENERGY STORAGESYSTEM 4 is allowed to simultaneously belong to two charging groups orto simultaneously belong to two discharging groups.

Subsequently, when the access control unit 425 authorizes access controlwith respect to two charge-discharge control devices 7 (EMSa and EMSb),the control authorization residual quantity becomes “0” as illustratedin FIG. 12A. Consequently, no control is allowed from a thirdcharge-discharge control device 7. Meanwhile, if simultaneous controlfrom a plurality of charge-discharge control devices 7 is not allowed,that is, if the BATTERY UNIT 40 is not sharable; then the controlauthorization residual quantity has the initial value of “1”. This isthe same concept as the concept of semaphore for performing accesscontrol with respect to the common resources of a standard databaseserver.

As illustrated in FIG. 12B, the characteristics information stored inthe memory unit 426 is identical to the characteristics informationstored in the memory unit 73. In the characteristics information, “type”indicates the types of electric power devices such as the ENERGY STORAGESYSTEM 4, the RENEWABLES 22, the photovoltaic power generating device30, and the ENERGY STORAGE SYSTEM 24 (heat accumulator device). Thus,“type” is used by the charge-discharge control device 7 in identifyingthe charging group or the discharging group to which an electric powerdevice should belong. For example, the RENEWABLES 22 is identified as adedicated device for performing only discharging, while a heataccumulator device is identified as a dedicated device for performingonly charging.

The operation control information is used in identifying the operationcondition (charge-discharge operation condition) of the ENERGY STORAGESYSTEM 4.

The charge-discharge managing unit 427 processes charge-dischargedetermination information, which is related to the charge-dischargecontrol of the ENERGY STORAGE SYSTEM 4, as well as processescharge-discharge electric power information; and outputs thatinformation to the access control unit 425. FIGS. 13A and 13B is adiagram illustrating a configuration example of the charge-dischargedetermination information and a configuration example of thecharge-discharge electric power information processed by thecharge-discharge managing unit 427.

The charge-discharge determination information is used to indicatewhether or not the BATTERY UNIT 40 is allowed to simultaneously belongto a plurality of charging groups or to simultaneously belong to aplurality of discharging groups, so that it becomes possible to identifywhether or not charge-discharge control can be simultaneously performedby a plurality of charge-discharge control devices 7 by referring tophysical constraint conditions of the BATTERY UNIT 40. For example, asillustrated in FIG. 13A, the charge-discharge determination informationindicates that a charge request at the time of charging is allowed and adischarge request at the time of discharging is allowed. For example,when the control authorization residual quantity that is specified inthe access control information illustrated in FIG. 12A has the initialvalue of “1”, if a new charge request at the time of charging is notallowed, then the charge-discharge managing unit 427 determines that theBATTERY UNIT 40 is not allowed to simultaneously belong to a pluralityof charging groups or to simultaneously belong to a plurality ofdischarging groups.

The charge-discharge electric power information is used in managing theallowed amount of electric energy (present values or planned values)assigned to a plurality of charge-discharge control device 7. Forexample, as illustrated in FIG. 13B, the charge-discharge electric powerinformation contains rated discharge electric power indicated in unitwatt (W: watt); rated charge electric power indicated in unit watt (W:watt); dischargeable time that is continually-updated while performingcharging and discharging; chargeable time that is continually-updatedwhile performing charging and discharging; and allowed electric energy.

FIG. 14 is a graph illustrating a case when the ENERGY STORAGE SYSTEM 4simultaneously receives discharge control instructions from twocharge-discharge control devices 7 (EMSa and EMSb) according to theallowed electric energy specified in the charge-discharge electric powerinformation.

The information control unit 424 generates a communication message,which is related to electric energy information or access control thatis required for performing charging and discharging control and that isobtained by the PCS (FIRST CONTROL UNIT) 42 from the BATTERY UNIT 40;and sends that communication message to the charge-discharge controldevice 7 via the first communicating unit 421.

The information obtaining unit 423 periodically obtains, via the secondcommunicating unit 422, the characteristics information described aboveas well as condition information (SOC, SOH, charge-discharge current,and charge-discharge voltage) that is the fluctuation information at thetime of operation of the BATTERY UNIT 40.

The first communicating unit 421 includes a transmitting unit 421 a anda receiving unit 421 b, and performs communication with thecharge-discharge control device 7 via the network 16.

The second communicating unit 422 includes a transmitting unit 422 a anda receiving unit 422 b, and performs communication with the BATTERY UNIT40 via the CAN 18.

Explained below are the operations performed by the charge-dischargecontrol device 7. FIG. 15 is a flowchart for explaining a sequence ofoperations performed by the charge-discharge control device 7. Asillustrated in FIG. 15, firstly, the charge-discharge control device 7obtains (receives) the schedule information that is set in each ENERGYSTORAGE SYSTEM 4 as well as receives the characteristics information andthe feasibility information of the BATTERY UNIT 40 either from eachENERGY STORAGE SYSTEM 4 or from another charge-discharge control device7 (Step S100).

Then, the charge-discharge control device 7 determines whether or notthe schedule information contains the scheduled time such as the starttime of charging and the end time of charging or the start time ofdischarging and the end time of discharging (Step S102). If thecharge-discharge control device 7 determines that the scheduled time isspecified (Yes at Step S102), then the system control proceeds to StepS104. On the other hand, if the charge-discharge control device 7determines that the scheduled time is not specified (No at Step S102),then the system control proceeds to Step S118.

Then, according to the feasibility information obtained at Step S100,the charge-discharge control device 7 determines whether or not theENERGY STORAGE SYSTEM 4 is sharable (Step S104). If the charge-dischargecontrol device 7 determines that the ENERGY STORAGE SYSTEM 4 is sharable(Yes at Step S104), then the system control proceeds to Step S106. Onthe other hand, if the charge-discharge control device 7 determines thatthe ENERGY STORAGE SYSTEM 4 is not sharable (No at Step S104), then thesystem control proceeds to Step S112.

Subsequently, the charge-discharge control device 7 performs first-timegrouping (Step S106). During the first-time grouping, firstly, thecharge-discharge control device 7 puts each ENERGY STORAGE SYSTEM 4 in acharging group or in a discharging group in accordance with the chargingoperation or the discharging operation specified in the scheduleinformation. Then, the charge-discharge control device 7 puts eachENERGY STORAGE SYSTEM 4 in a charging group or in a discharging group inaccordance with the scheduled time specified in the scheduleinformation. Herein, the charge-discharge control device 7 performsgrouping according to the feasibility information in such a way thateach ENERGY STORAGE SYSTEM 4 simultaneously belongs to the number ofcharging groups or the number of discharging groups that is equal to orsmaller than the control authorization residual quantity.

Subsequently, according to the assigned amount of electric power withrespect to the charging groups or the discharging groups that is set inthe ENERGY STORAGE SYSTEM 4 whose feasibility information has beenreceived as well as according to the condition calculating informationthat enables derivation of the chargeable time and the rated value; thecharge-discharge control device 7 adds the assigned amount (electricenergy), which is set for the ENERGY STORAGE SYSTEM 4 whose feasibilityinformation has been received, to the electric energy of each charginggroup or to the electric energy of each discharging group, andcalculates the total amount of charging of each charging group or thetotal amount of discharging of each discharging group (Step S108).

Then, the charge-discharge control device 7 sets a period of validity insuch a way that, for example, the time at which the schedule time forperforming charging or discharging as specified in the scheduleinformation ends for the first time within a charging group or within adischarging group serves as the validity time limit for charging groupsor discharging groups (Step S110).

Subsequently, the charge-discharge control device 7 performs second-timegrouping (Step S112). During the second-time grouping, firstly, thecharge-discharge control device 7 puts each ENERGY STORAGE SYSTEM 4 in acharging group or in a discharging group in accordance with the chargingoperation or the discharging operation specified in the scheduleinformation. Then, the charge-discharge control device 7 puts eachENERGY STORAGE SYSTEM 4 in a charging group or in a discharging group inaccordance with the scheduled time specified in the scheduleinformation. Herein, the charge-discharge control device 7 performsgrouping in such a way that the ENERGY STORAGE SYSTEM 4 that is notallowed to simultaneously belong to a plurality of charging groups or aplurality of discharging groups is not simultaneously put in a pluralityof charging groups or in a plurality of discharging groups and in such away that the ENERGY STORAGE SYSTEM 4 belongs either to one or morecharging groups or to one or more discharging groups.

Then, the charge-discharge control device 7 adds, according to theschedule information, the rated value of the charged electric energy orthe rated value of the discharged electric energy of the ENERGY STORAGESYSTEM 4 whose feasibility information has been received, to theelectric energy of each charging group or to the electric energy of eachdischarging group, and calculates the total amount of charging of eachcharging group or calculates the total amount of discharging of eachdischarging group (Step S114).

Subsequently, the charge-discharge control device 7 sets a period ofvalidity in such a way that, for example, the time at which the scheduletime for performing charging or discharging as specified in the scheduleinformation ends for the first time within a charging group or within adischarging group serves as the validity time limit for charging groupsor discharging groups (Step S116).

Then, according to the feasibility information obtained at Step S100,the charge-discharge control device 7 determines whether or not theENERGY STORAGE SYSTEM 4 is sharable (Step S118). If the charge-dischargecontrol device 7 determines that the ENERGY STORAGE SYSTEM 4 is sharable(Yes at Step S118), then the system control proceeds to Step S120. Onthe other hand, if the charge-discharge control device 7 determines thatthe ENERGY STORAGE SYSTEM 4 is not sharable (No at Step S118), then thesystem control proceeds to Step S124.

Subsequently, the charge-discharge control device 7 performs third-timegrouping (Step S120). During the third-time grouping, thecharge-discharge control device 7 puts each ENERGY STORAGE SYSTEM 4 inan arbitrary charging group or in an arbitrary discharging group.Herein, the charge-discharge control device 7 performs groupingaccording to the feasibility information in such a way that each ENERGYSTORAGE SYSTEM 4 simultaneously belongs to a number of charging groupsor a number of discharging groups that is equal to or smaller than thecontrol authorization residual quantity.

Then, according to the assigned amount of electric power with respect tothe charging groups or the discharging groups that is set in the ENERGYSTORAGE SYSTEM 4 whose feasibility information has been received as wellas according to the condition calculating information that enablesderivation of the chargeable time and the rated value; thecharge-discharge control device 7 adds the assigned amount (electricenergy), which is set for the ENERGY STORAGE SYSTEM 4 whose feasibilityinformation has been received to the electric energy of each charginggroup or to the electric energy of each discharging group, andcalculates the total amount of charging of each charging group or thetotal amount of charging of each discharging groups (Step S122).

Subsequently, the charge-discharge control device 7 performs fourth-timegrouping (Step S124). During the fourth-time grouping, thecharge-discharge control device 7 puts each ENERGY STORAGE SYSTEM 4 in acharging group or a discharging group. Herein, the charge-dischargecontrol device 7 performs grouping in such a way that the ENERGY STORAGESYSTEM 4 that is not allowed to simultaneously belong to a plurality ofcharging groups or a plurality of discharging groups is notsimultaneously put in a plurality of charging groups or a plurality ofdischarging groups and in such a way that the ENERGY STORAGE SYSTEM 4belongs either to one or more charging groups or to one or moredischarging groups.

Then, the charge-discharge control device 7 adds, according to theschedule information, the rated value of the charged electric energy orthe rated value of the discharged electric energy of the ENERGY STORAGESYSTEM 4 whose feasibility information has been received, to theelectric energy of each charging group or to the electric energy of eachdischarging group, and calculates the total amount of charging of eachcharging group or the total amount of discharging of each discharginggroup (Step S126).

Explained below are operation examples (first operation example tofourth operation examples) of the charge-discharge control system 1.FIG. 16 is a sequence diagram illustrating operation examples of thecharge-discharge control system 1. In FIG. 16, it is assumed that thecharge-discharge control system 1 includes, for example, a singlecharge-discharge control device 7 a (EMSa) and three ENERGY STORAGESYSTEMs 4 a, 4 b, and 4 c (ENERGY STORAGE SYSTEMs a, b, and c).

First Operation Example

Each of the ENERGY STORAGE SYSTEMs 4 a, 4 b, and 4 c performscharge-discharge control according to a schedule. Moreover, it isassumed that the ENERGY STORAGE SYSTEM 4 a (ENERGY STORAGE SYSTEM a) andthe ENERGY STORAGE SYSTEM 4 b (ENERGY STORAGE SYSTEM b) are assigned tobelong to the same discharging group.

Herein, in the case when a charge-discharge control device 7 a performsgrouping to put the ENERGY STORAGE SYSTEM 4 c (ENERGY STORAGE SYSTEM c)in a charging group or in a discharging group; the charge-dischargecontrol device 7 a (EMSa) receives and obtains, from the ENERGY STORAGESYSTEM 4 c, BATTERY UNIT information that contains characteristicsinformation, charge-discharge control information, and feasibilityinformation. For example, the charge-discharge control device 7 areceives communication messages illustrated in FIGS. 17A and 17B.

The communication message illustrated in FIG. 17A is sent by the ENERGYSTORAGE SYSTEM 4 to the charge-discharge control device 7 and containsthe schedule information. For example, the communication messageillustrated in FIG. 17A contains a communication header of TCP/IP, anidentifier used in identifying the message contents, the count of thecharge-discharge control devices 7, the start time of performingcharging or discharging, the end time of performing charging ordischarging, and information indicating charge-discharge electric power.

The communication message illustrated in FIG. 17B is sent by the ENERGYSTORAGE SYSTEM 4 to the charge-discharge control device 7 and containsthe feasibility information and the characteristics information. Forexample, the communication message illustrated in FIG. 17B contains acommunication header of TCP/IP, an identifier used in identifying themessage contents, the access control information, the BATTERY UNITcharacteristics information, and the charge-discharge controlinformation.

The BATTERY UNIT information of the ENERGY STORAGE SYSTEM 4 c has theschedule information (the charge-discharge control information) settherein, and it is assumed that the feasibility information allowssharing. As illustrated in FIG. 18, for example, during the timeinterval t1, with respect to a rated discharge electric power of W1 wattof the ENERGY STORAGE SYSTEM 4 c, it is assumed that an assigneddischarge electric power of w10 watt is already assigned to anothercharge-discharge control device 7.

Thus, during the time interval (discharge period) t1, thecharge-discharge control device 7 a determines that the electric powerequal to (W1-w10) watt can be assigned for discharge control to beperformed by itself. In the time interval (charge period) t2 after theelapse of the time interval t1, the ENERGY STORAGE SYSTEM 4 c assigns anentire amount of a rated charge electric power of W2 watt for chargecontrol. That is, in the time interval t2 after the elapse of the timeinterval t1, the charge-discharge control device 7 a cannot assign theENERGY STORAGE SYSTEM 4 c for the purpose of charge-discharge control.

After determining the condition of the ENERGY STORAGE SYSTEM 4 c byreferring to the BATTERY UNIT information, the charge-discharge controldevice 7 a determines the group in which the ENERGY STORAGE SYSTEM 4 cis to be put. FIG. 19 is a schematic diagram that schematicallyillustrates the assignment of electric power in the first-time grouping.In FIG. 19, it is assumed that the charge-discharge control device 7 acontrols a plurality of groups including the discharging group A. Moreparticularly, it is assumed that the charge-discharge control device 7 ahas already assigned the ENERGY STORAGE SYSTEM 4 a having an identifierX and the ENERGY STORAGE SYSTEM 4 b having an identifier Y to thedischarging group A.

Herein, the ENERGY STORAGE SYSTEM 4 c having an identifier Z has theschedule information (the charge-discharge control information) settherein, and it is assumed that the feasibility information allowssharing. Therefore, the ENERGY STORAGE SYSTEM 4 c becomes the target ofnew addition to the discharging group A. Thus, the charge-dischargecontrol device 7 performs grouping so as to put the ENERGY STORAGESYSTEM 4 c in the discharging group A, and adds the assigned dischargeelectric power of the ENERGY STORAGE SYSTEM 4 c to the total electricpower of the discharging group A.

More particularly, the charge-discharge control device 7 a updates theinformation illustrated in FIG. 9 and FIG. 10 to the information relatedto the total amount of charging and discharging. Once the grouping iscomplete, the charge-discharge control device 7 a can send acommunication message regarding the updated discharging group to theENERGY STORAGE SYSTEMs 4 a, 4 b, and 4 c. For example, thecharge-discharge control device 7 a sends a communication messageillustrated in FIG. 17C.

The communication message illustrated in FIG. 17C is sent by thecharge-discharge control device 7 to the ENERGY STORAGE SYSTEM 4 andcontains the charge-discharge control information. For example, thecommunication message illustrated in FIG. 17C contains a communicationheader of TCP/IP, an identifier used in identifying the messagecontents, the count of the charge-discharge control devices 7, theinformation indicating the charging groups and the discharging groups,and the BATTERY UNIT identifiers. Meanwhile, the charge-dischargecontrol device 7 a can set the BATTERY UNIT information in advance andobtain it. Moreover, the format of the communication messages is notlimited to the format illustrated in FIGS. 17A to 17C, and any otherformat can be used.

The discharging group A has the period of validity equal to the timeinterval t1. The schedule information is set in such a way that, afterthe elapse in the time interval t1, the ENERGY STORAGE SYSTEM 4 bperforms not the discharge control but the charge control. That is, theend time of the discharge period t1 is the validity time limit of thedischarging group A. Once the period of validity of the discharginggroup A is over, the charge-discharge control device 7 a reconfiguresthe group to which belongs the ENERGY STORAGE SYSTEM 4 for which theperiod of validity is over. Meanwhile, as the communication messagerelated to a discharge control instruction, the charge-discharge controldevice 7 a can use a communication message that indicates the start ofcontrol. Moreover, in the scheduled-operation control in which theschedule time for performing charging or discharging is set in advance,the charge-discharge control device 7 a may skip sending thecommunication message related to a discharge control instruction.

Second Operation Example

Each of the ENERGY STORAGE SYSTEMs 4 a, 4 b, and 4 c performscharge-discharge control according to a schedule. Moreover, it isassumed that the ENERGY STORAGE SYSTEM 4 a (ENERGY STORAGE SYSTEM a) andthe ENERGY STORAGE SYSTEM 4 b (ENERGY STORAGE SYSTEM b) are assigned tobelong to the same discharging group.

The charge-discharge control device 7 a selects the charging groups orthe discharging groups to which the ENERGY STORAGE SYSTEM 4 c (theENERGY STORAGE SYSTEM c) should belong. Herein, from the ENERGY STORAGESYSTEM 4 c (the ENERGY STORAGE SYSTEM c), the charge-discharge controldevice 7 a (EMSa) receives and obtains the BATTERY UNIT information thatcontains the charge-discharge control information and the feasibilityinformation. For example, the charge-discharge control device 7 areceives the communication messages illustrated in FIGS. 17A and 17B.

The BATTERY UNIT information of the ENERGY STORAGE SYSTEM 4 c has theschedule information (the charge-discharge control information), and thefeasibility information does not allow sharing. Herein, as illustratedin FIG. 20, for example, during the time interval t1, the ENERGY STORAGESYSTEM 4 c determines that charging or discharging is not scheduled andthat the total capacity of W1 watt of the rated discharge electric powercan be assigned to the discharge control performed by thecharge-discharge control device 7.

In the time interval (charge period) t2 after the elapse of the timeinterval t1, the ENERGY STORAGE SYSTEM 4 c assigns the entire amount ofthe rated charge electric power of W2 watt for charge control. That is,in the time interval t2 after the elapse of the time interval t1, thecharge-discharge control device 7 a cannot assign the ENERGY STORAGESYSTEM 4 c for the purpose of charge-discharge control.

After determining the condition of the ENERGY STORAGE SYSTEM 4 c byreferring to the BATTERY UNIT information, the charge-discharge controldevice 7 a determines the group in which the ENERGY STORAGE SYSTEM 4 cis to be put. FIG. 21 is a schematic diagram that schematicallyillustrates the assignment of electric power in the second-timegrouping. In FIG. 21, it is assumed that the charge-discharge controldevice 7 a controls a plurality of groups including the discharginggroup A. More particularly, it is assumed that the charge-dischargecontrol device 7 a has already assigned the ENERGY STORAGE SYSTEM 4 ahaving the identifier X and the ENERGY STORAGE SYSTEM 4 b having theidentifier Y to the discharging group A.

Herein, the ENERGY STORAGE SYSTEM 4 c having the identifier Z has theschedule information (the charge-discharge control information) settherein, and it is assumed that the feasibility information does notallow sharing. Therefore, the ENERGY STORAGE SYSTEM 4 c becomes thetarget of new addition to the discharging group A. Thus, thecharge-discharge control device 7 performs grouping so as to put theENERGY STORAGE SYSTEM 4 c in the discharging group A, and adds the rateddischarge electric power of the ENERGY STORAGE SYSTEM 4 c to the totalelectric power of the discharging group A.

More particularly, the charge-discharge control device 7 a updates theinformation illustrated in FIG. 9 and FIG. 10 to the information relatedto the total amount of charging and discharging. Once the grouping iscomplete, the charge-discharge control device 7 a can send acommunication message regarding the updated discharging group to theENERGY STORAGE SYSTEMs 4 a, 4 b, and 4 c. For example, thecharge-discharge control device 7 a sends a communication messageillustrated in FIG. 17C.

The communication message illustrated in FIG. 17C is sent by thecharge-discharge control device 7 to the ENERGY STORAGE SYSTEM 4 andcontains the charge-discharge control information. For example, thecommunication message illustrated in FIG. 17C contains a communicationheader of TCP/IP, an identifier used in identifying the messagecontents, the count of the charge-discharge control devices 7, theinformation indicating the charging groups and the discharging groups,and the BATTERY UNIT identifiers. Meanwhile, the charge-dischargecontrol device 7 a can set the BATTERY UNIT information in advance andobtain it. Moreover, the format of the communication messages is notlimited to the format illustrated in FIGS. 17A to 17C, and any otherformat can be used.

The discharging group A has the period of validity equal to the timeinterval t1. The schedule information is set in such a way that, afterthe elapse in the time interval t1, the ENERGY STORAGE SYSTEM 4 bperforms not the discharge control but the charge control. That is, theend time of the discharge period t1 is the validity time limit of therndischarging group A. Once the period of validity of the discharginggroup A is over, the charge-discharge control device 7 a reconfiguresthe group to which belongs the ENERGY STORAGE SYSTEM 4 for which theperiod of validity is over. Meanwhile, as the communication messagerelated to a discharge control instruction, the charge-discharge controldevice 7 a can use a communication message that indicates the start ofcontrol. Moreover, in scheduled-operation control in which the scheduletime for performing charging or discharging is set in advance, thecharge-discharge control device 7 a may skip sending the communicationmessage related to a discharge control instruction.

Third Operation Example

Each of the ENERGY STORAGE SYSTEMs 4 a, 4 b, and 4 c performscharge-discharge control on the on-demand basis. Moreover, it is assumedthat the ENERGY STORAGE SYSTEM 4 a (ENERGY STORAGE SYSTEM a) and theENERGY STORAGE SYSTEM 4 b (ENERGY STORAGE SYSTEM b) are assigned tobelong to the same discharging group.

The charge-discharge control device 7 a selects the charging groups orthe discharging groups to which the ENERGY STORAGE SYSTEM 4 c (theENERGY STORAGE SYSTEM c) should belong. Herein, from the ENERGY STORAGESYSTEM 4 c (the ENERGY STORAGE SYSTEM c), the charge-discharge controldevice 7 a (EMSa) receives and obtains the BATTERY UNIT information thatcontains characteristics information, charge-discharge controlinformation, and feasibility information. For example, thecharge-discharge control device 7 a receives the communication messagesillustrated in FIGS. 17A and 17B.

The BATTERY UNIT information of the ENERGY STORAGE SYSTEM 4 c does nothave the schedule information (the charge-discharge control information)set therein, and it is assumed that the feasibility information allowssharing. As illustrated in FIG. 20, for example, the ENERGY STORAGESYSTEM 4 c determines that an arbitrary amount from the rated dischargeelectric power of W1 watt can be assigned to the discharge controlperformed by the charge-discharge control device 7.

Moreover, the ENERGY STORAGE SYSTEM 4 c is not scheduled to assign therated charge-discharge electric power for charge control. Thus, thecharge-discharge control device 7 a can assign the ENERGY STORAGE SYSTEM4 c for charge-discharge control.

After determining the condition of the ENERGY STORAGE SYSTEM 4 c byreferring to the BATTERY UNIT information, the charge-discharge controldevice 7 a determines the group in which the ENERGY STORAGE SYSTEM 4 cis to be put. As illustrated in FIG. 19, it is assumed that thecharge-discharge control device 7 a controls a plurality of groupsincluding the discharging group A. More particularly, it is assumed thatthe charge-discharge control device 7 a has already assigned the ENERGYSTORAGE SYSTEM 4 a having the identifier X and the ENERGY STORAGE SYSTEM4 b having the identifier Y to the discharging group A.

Herein, the ENERGY STORAGE SYSTEM 4 c having the identifier Z does nothave the schedule information (the charge-discharge control information)set therein, and it is assumed that the feasibility information allowssharing. Therefore, the ENERGY STORAGE SYSTEM 4 c becomes the target ofnew addition to the discharging group A. Thus, the charge-dischargecontrol device 7 a performs grouping so as to put the ENERGY STORAGESYSTEM 4 c in the discharging group A, and adds the assigned dischargeelectric power of the ENERGY STORAGE SYSTEM 4 c to the total electricpower of the discharging group A.

More particularly, the charge-discharge control device 7 a updates theinformation illustrated in FIG. 9 and FIG. 10 to the information relatedto the total amount of charging and discharging. Once the grouping iscomplete, the charge-discharge control device 7 a can send acommunication message regarding the updated discharging group to theENERGY STORAGE SYSTEMs 4 a, 4 b, and 4 c. For example, thecharge-discharge control device 7 a sends the communication messageillustrated in FIG. 17C.

As the communication message related to a discharge control instruction,the charge-discharge control device 7 a can use a communication messagethat indicates the start of control. Moreover, in scheduled-operationcontrol in which the schedule time, for performing charging ordischarging is set in advance, the charge-discharge control device 7 amay skip sending the communication message related to a dischargecontrol instruction.

Meanwhile, the charge-discharge control device 7 a can also beconfigured in such a way that, during the period when the operations arebeing performed according to a schedule, the charge-discharge controldevice 7 a performs operations identical to the third operation exampleeven with respect to the interval of time in which a schedule period forperforming charging or discharging is not set.

Fourth Operation Example

Each of the ENERGY STORAGE SYSTEMs 4 a, 4 b, and 4 c performscharge-discharge control on the on-demand basis. Moreover, it is assumedthat the ENERGY STORAGE SYSTEM 4 a (ENERGY STORAGE SYSTEM a) and theENERGY STORAGE SYSTEM 4 b (ENERGY STORAGE SYSTEM b) are assigned tobelong to the same discharging group.

The charge-discharge control device 7 a selects the charging groups orthe discharging groups to which the ENERGY STORAGE SYSTEM 4 c (theENERGY STORAGE SYSTEM c) should belong. Herein, from the ENERGY STORAGESYSTEM 4 c (the ENERGY STORAGE SYSTEM c), the charge-discharge controldevice 7 a (EMSa) receives and obtains the BATTERY UNIT information thatcontains characteristics information, charge-discharge controlinformation, and feasibility information. For example, thecharge-discharge control device 7 a receives the communication messagesillustrated in FIGS. 17A and 17B.

The BATTERY UNIT information of the ENERGY STORAGE SYSTEM 4 c does nothave the schedule information (the charge-discharge control information)set therein, and it is assumed that the feasibility information does notallow sharing. Herein, for example, the ENERGY STORAGE SYSTEM 4 c is notscheduled to performing charging or discharging and determines that thetotal amount of the rated discharge electric power of W1 watt can beassigned to the discharge control performed by the charge-dischargecontrol device 7.

Moreover, the ENERGY STORAGE SYSTEM 4 c is not scheduled to assign therated charge-discharge electric power for charge control. Thus, thecharge-discharge control device 7 a can assign the ENERGY STORAGE SYSTEM4 c for charge-discharge control.

After determining the condition of the ENERGY STORAGE SYSTEM 4 c byreferring to the BATTERY UNIT information, the charge-discharge controldevice 7 a determines the group in which the ENERGY STORAGE SYSTEM 4 cis to be put. As illustrated in FIG. 21, it is assumed that thecharge-discharge control device 7 a controls a plurality of groupsincluding the discharging group A. More particularly, it is assumed thatthe charge-discharge control device 7 a has already assigned the ENERGYSTORAGE SYSTEM 4 a having the identifier X and the ENERGY STORAGE SYSTEM4 b having the identifier Y to the discharging group A.

Herein, the ENERGY STORAGE SYSTEM 4 c having the identifier Z does nothave the schedule information (the charge-discharge control information)set therein, and it is assumed that the feasibility information does notallow sharing. Therefore, the ENERGY STORAGE SYSTEM 4 c becomes thetarget of new addition to the discharging group A. Thus, thecharge-discharge control device 7 a performs grouping so as to put theENERGY STORAGE SYSTEM 4 c in the discharging group A, and adds the rateddischarge electric power of the ENERGY STORAGE SYSTEM 4 c to the totalelectric power of the discharging group A.

More particularly, the charge-discharge control device 7 a updates theinformation illustrated in FIG. 9 and FIG. 10 to the information relatedto the total amount of charging and discharging. Once the grouping iscomplete, the charge-discharge control device 7 a can send acommunication message regarding the updated discharging group to theENERGY STORAGE SYSTEMs 4 a, 4 b, and 4 c. For example, thecharge-discharge control device 7 a sends the communication messageillustrated in FIG. 17C.

As the communication message related to a discharge control instruction,the charge-discharge control device 7 a can use a communication messagethat indicates the start of control. Moreover, in scheduled-operationcontrol in which the schedule time for performing charging ordischarging is set in advance, the charge-discharge control device 7 amay skip sending the communication message related to a dischargecontrol instruction.

Meanwhile, the charge-discharge control device 7 a can also beconfigured in such a way that, during the period when the operations arebeing performed according to a schedule, the charge-discharge controldevice 7 a performs operations identical to the fourth operation exampleeven with respect to the interval of time in which a schedule period forperforming charging or discharging is not set.

The charge-discharge control device 7 according to the embodiment has,for example, a hardware configuration of a commonplace computer thatincludes a control device such as a central processing unit (CPU), amemory device such as a read only memory (ROM) or a random access memory(RAM), an external memory device such as a hard disk drive (HDD) or acompact disk (CD) drive device, a display device such as a display, andan input device such as a keyboard or a mouse.

A charge-discharge control program executed in the charge-dischargecontrol device 7 according to the embodiment is recorded in the form ofan installable or executable file on a computer-readable recordingmedium such as a compact disk read only memory (CD-ROM), a flexible disk(FD), a compact disk recordable (CD-R), or a digital versatile disk(DVD).

Alternatively, the charge-discharge control program executed in thecharge-discharge control device 7 according to the embodiment can besaved in a downloadable manner on a computer connected to the Internet.Still alternatively, the charge-discharge control program executed inthe charge-discharge control device 7 according to the embodiment can bedistributed over a network such as the Internet.

Still alternatively, the charge-discharge control program executed inthe charge-discharge control device 7 according to the embodiment can bestored in advance in, for example, a ROM. The charge-discharge controlprogram executed in the charge-discharge control device 7 according tothe embodiment contains modules for each of the abovementionedconstituent elements (the receiving unit 712 and the group control unit74). In practice, for example, a CPU (processor) reads thecharge-discharge control program from the recording medium mentionedabove and runs it so that the charge-discharge control program is loadedin main memory device. As a result, the module for each of the receivingunit 712 and the group control unit 74 is generated in the main memorydevice.

As described above, according to the embodiment, even if there is anincrease in the number of electric power devices that are connected to anetwork, it becomes possible to perform communication in an efficientmanner.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. A charge-discharge control device comprising: areceiving unit configured to receive schedule information that indicatesa schedule time at which a plurality of electric power devices, eachhaving at least either a charging function or a discharging function,performs at least either charging or discharging; and a group controllerconfigured to, according to the schedule information, perform groupingin such a way that each of the electric power devices belongs to eitherone of a charging group for performing charging and a discharging groupfor performing discharging.
 2. The device according to claim 1, whereinthe receiving unit further receives characteristics information thatindicates electric power characteristics including a rated value of eachof the plurality of electric power devices, and the device furthercomprising a calculator configured to, according to the characteristicsinformation, calculate a total amount of charging of the charging groupand calculates a total amount of discharging of the discharging group.3. The device according to claim 2, wherein each of the electric powerdevices has feasibility information set therein that indicates whetheror not it is allowed to simultaneously receive a plurality of differentcharge controls, the receiving unit further receives the feasibilityinformation, the device further comprising a determining unit configuredto, according to the feasibility information, determine whether or notthe electric power device is allowed to simultaneously receive aplurality of charge controls, and according to a determination result ofthe determining unit and according to the schedule information, thegroup controller performs the grouping in such a way that the electricpower device that is not allowed to simultaneously receive a pluralityof charge controls do not simultaneously receive a plurality of chargecontrols and in such a way that the electric power devices belong to oneor more charging groups, and controls the electric power devices put inthe charging groups on the group-by-group basis.
 4. The device accordingto claim 2, wherein, each of the electric power devices has feasibilityinformation set therein that indicates whether or not it is allowed tosimultaneously receive a plurality of different discharge controls, thereceiving unit further receives the feasibility information, thecharge-discharge control device further includes a determining unitconfigured to, according to the feasibility information, determineswhether or not the electric power device is allowed to simultaneouslyreceive a plurality of discharge controls, and according to adetermination result of the determining unit and according to theschedule information, the group controller performs the grouping in sucha way that the electric power device that is not allowed tosimultaneously receive a plurality of discharge controls do notsimultaneously receive a plurality of discharge controls and in such away that the electric power devices belong to one or more discharginggroups, and controls the electric power devices put in the discharginggroups on the group-by-group basis.
 5. The device according to claim 3,wherein, as a period of validity of the charging groups, the groupcontrol unit sets an interval of time in which the schedule time forperforming charging as specified in the schedule information ends forthe first time within the charging groups.
 6. The device according toclaim 4, wherein, as a period of validity of the discharging groups, thegroup control unit sets an interval of time in which the schedule timefor performing discharging as specified in the schedule information endsfor the first time within the discharging groups.
 7. The deviceaccording to claim 3, wherein the receiving unit receives conditioncalculating information that enables derivation of a chargeable time anda rated value of each of the plurality of electric power devices, andwhen the determining unit determines that the electric power devicesthat have received the feasibility information are allowed tosimultaneously receive a plurality of different charge controls, thecalculator calculates a total amount of charging of each charging groupaccording to an amount of assigned electric power set for the electricpower device whose feasibility information has been received andaccording to the condition calculating information.
 8. The deviceaccording to claim 4, wherein the receiving unit receives conditioncalculating information that enables derivation of a dischargeable timeand a rated value of each of the plurality of electric power devices,and when the determining unit determines that the electric power devicesthat have received the feasibility information are allowed tosimultaneously receive a plurality of different discharge controls, thecalculator calculates a total amount of discharging of each discharginggroup according to an amount of assigned electric power set for theelectric power device whose the feasibility information has beenreceived and according to the condition calculating information.
 9. Thedevice according to claim 7, wherein, when the determining unitdetermines that the electric power device whose feasibility informationhas been received is not allowed to simultaneously receive a pluralityof different charge controls, the calculator calculates a total amountof charging of each charging group according to the rated value of theelectric power device whose feasibility information has been received.10. The device according to claim 8, wherein, when the determining unitdetermines that the electric power device whose feasibility informationhas been received is not allowed to simultaneously receive a pluralityof different discharge controls, the calculator calculates a totalamount of discharging of each discharging group according to the ratedvalue of the electric power device whose feasibility information hasbeen received.
 11. The device according to claim 3, wherein, at leastone of the electric power devices is a photovoltaic power generatingdevice, and when the feasibility information of the photovoltaic powergenerating device is received, the group controller performs grouping insuch a way that the photovoltaic power generating device belongs to thedischarging group, and the calculator calculates a total amount ofdischarging of the discharging group according to a rated value of thephotovoltaic power generating device.
 12. The device according to claim4, wherein, at least one of the electric power devices is a heataccumulator device, when the feasibility information of the heataccumulator device is received, the group controller performs groupingin such a way that the heat accumulator device belongs to the charginggroup, and the calculator calculates a total amount of charging of thecharging group according to a rated value of the heat accumulatordevice.
 13. The device according to claim 5, wherein the groupcontroller again performs grouping with respect to the charging groupsto which belonged the electric power devices that are disconnected forcommunication from the receiving unit and with respect to the charginggroups that have reached the period of validity.
 14. The deviceaccording to claim 6, wherein, as a period of validity of the charginggroups, the group control unit sets an interval of time in which theschedule time for performing charging as specified in the scheduleinformation ends for the first time within the charging groups.
 15. Thedevice according to claim 1, wherein at least one of the plurality ofelectric power devices includes a BATTERY UNIT.
 16. The device accordingto claim 1, wherein the receiving unit receives the schedule informationeither from “one of the electric power devices” or from anothercharge-discharge control device.
 17. A charge-discharge control systemcomprising: a plurality of electric power devices each having at leasteither a charging function or a discharging function; and acharge-discharge control device that controls the plurality of electricpower devices, wherein the charge-discharge control device includes areceiving unit configured to receive schedule information that indicatesa schedule time at which the plurality of electric power devices performat least either charging or discharging; and a group controllerconfigured to, according to the schedule information, perform groupingin such a way that each of the electric power devices belongs to eitherone of a charging group for performing charging and a discharging groupfor performing discharging, and control, on a group-by-group basis, eachof the electric power devices put in the charging group and each of theelectric power devices put in the discharging group.
 18. A computerprogram product comprising a computer-readable medium containing acharge-discharge control program that causes a computer to execute:receiving schedule information that indicates a schedule time at which aplurality of electric power devices, each having at least either acharging function or a discharging function, performs at least eithercharging or discharging; performing grouping, according to the scheduleinformation, in such a way that each of the electric power devicesbelongs to either one of a charging group for performing charging and adischarging group for performing discharging; and controlling, on agroup-by-group basis, each of the electric power devices put in thecharging group and each of the electric power devices put in thedischarging group.